The advantages of using fluidized-bed electrodes in various electrochemical processes such as electrowinning of metals from dilute solutions or electrosynthesis of organic materials are increasingly recognized. In the literature, the fluidized-bed electrode system is described as being basically composed of fine particles of metals or metal-coated glass or plastic beads contained in a suitably designed cell and fluidized by the passage of an electrolyte solution to be treated through the bed of particles. Electrical feeders in contact with the particulated bed and auxiliary electrodes complete the electrochemical circuit.
To obtain optimum performance from this type of fluidized-bed electrodes, it has been disclosed in the prior art that a bed expansion varying between 10 and 50% was necessary. To obtain bed expansions of these magnitudes, the electrolyte has to be circulated through the cell at a fixed flow rate depending mostly on the specific gravity of the electrolyte and of the particles to be fluidized, on the dimension of the particles and on the geometry of the cell. One important implication of this is that, to achieve any desired degree of completeness of an electrochemical reaction, that is complete removal of an ionic species from the electrolyte solution, it is often necessary to recirculate the solution through the fluidized-bed electrode cell or to mount plural cells in series. Another possible way of overcoming this problem is to increase the total height of the fluidized-bed electrode; however, this may lead to several difficulties in practice such as the necessity of introducing the electrolyte into the cell at a high pressure to overcome the pressure drop due to the weight of the particles composing the bed.